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Thanks then looks cost for have real time global system EQ end be a enourmous phase shift from DPA-1 units steep slope plus whatever slope inherent into speaker system. Filters look be of high order especially the one at at 500Hz so could imagine how square waves gets distorted there, if slope order could be dialed in manual and relaxed in settings to a much lower order it would help on that phase distortion aka group delay numbers, that said can't see myself would ever like have those filters into audio chain if they non removeable.

Typical examples of correctly rated gear (headline number service manual):

Notice the FTC rating on this example below has a slightly higher THD than the full power number as THD starts off higher at low powers and decreases towards maximum.

Below are typical preamplifier THD ratings:

Phono stage:

Line stages:

Notice the DIN power in the above examples at 1%THD at 1KHz and 4ohms. Nobody ever considered the EU DIN (or the IEC) ratings as anything useful back in the day. The only serious rating was the FTC and all the respectable manufacturers who wanted to sell gear in the US had to adhere to it. Now we have a global marketplace, with little impediment to importing gear directly. Stuff without c-tick, UL listings, etc. It's a nightmare.

Standards have lapsed to the point where specifications are a sad joke, and not to be trusted, and in many cases, blatantly deceptive and designed to paint their products in the best light as opposed to the old way, which was a worst case scenario.

The random examples above are from Denon, Yamaha, Pioneer and Sony and all those pieces are in my collection. They go to show that standards have not only lapsed across the board, but gone backwards a long way. All those pieces above are >20-30 years old...

Last edited: Feb 17, 2019

Ricky Roma: I subscribe to the law of contrary public opinion... If everyone thinks one thing, then I say, bet the other way...

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That's a pretty extreme statement, not least since the power amp specs you posted all quote single THD figures at rated power into different loads, the 'rated' figure varying according to the standard used.

Addicted to Fun and Learning

The problem with any standard is that to fully understand what approval (or conformity) against that standard actually means you have to have read and understood the standard. That may sound obvious, or it may sound silly, but standards define requirements and criteria, and it is worth keeping in mind that many of these standards are effectively written by manufacturers. I've been on a few ISO technical committees and hard, technical standards invariably rely on manufacturers simply because that's where the expertise is. The danger is always that certain manufacturers use the opportunity to push their own solution as an international standard. And many standards have promoted over optimisation for a certain performance point defined in standards with negative consequences for overall performance. When looking at standards I'm always reminded of the famous apocryphal story about how enthusiasts of sausages and laws should never take an interest in how either is made.

Addicted to Fun and Learning

That's a pretty extreme statement, not least since the power amp specs you posted all quote single THD figures at rated power into different loads, the 'rated' figure varying according to the standard used.

No, the 5 sample power amplifier figures quoted above are all FTC rated, which means the 250mW to full rated power across the 20Hz-20KHz bandwidth at the rated THD or less into an 8 ohm load with other loads as optional. That was the standard, the law, and what was expected back in the day.

The additional figures are for other standards, jurisdictions, alternative voltages etc.

What this small sample above shows is an European rated amplifier is held to much less stringent requirements than the old US FTC standard among other things. 1KHz, 1% versus 20-20 and 0.003% means an additional 36% more rated power in the case of the bottom example. An additional 25% in the case of the second from the bottom.

The issues are obvious. The same brochure printed in Germany for the example (2 up) above listed the amplifier as 150+150W whereas the same amplifier in the US is marketed at 120+120W. It happened for decades, but the good companies (like the ones listed above) would provide detailed specifications so anyone with a modicum of understanding could determine what was what.

Now we are presented with 'specifications' like your example shown above. Not only are they inadequate, they are incomplete and present more questions than answers. And, apparently coming from Crown of all people who should know a whole lot better.

The desire to hold manufacturers to account and at least demand already existing standards be rigorously applied, seems to have fallen by the wayside and be unfashionable these days.

Ricky Roma: I subscribe to the law of contrary public opinion... If everyone thinks one thing, then I say, bet the other way...

Member

This is part one of the review and detailed measurements of Lyngdorf TDAI-3400 Integrated amplifier, streamer, DAC and Room equalizer. It is on kind loan from a member and costs USD $6,499 (£4,995.00). In this review I will be focusing on the overall features of the unit, and performance of its DAC and amplifier subsystems. In part 2 I will be hooking it up to my main system to test the RoomPerfect room equalization feature.

Note: Lyngdorf is now owned by Steinway whose products are used/sold by my company Madrona Digital. So feel free to read as much or as little bias as you feel is right into my review.
...
If you are not familiar with Lyngdorf, it is one of the earliest pioneers of room equalization. Indeed when Harman decided to develop its own (ARCOS) it used the Lyngdorf as a benchmark to beat. The Lyngdorf did very well in their double blind tests.
...
Let's get into measurements and see how she does.

A couple comments:
1) Lyngdorf (AKA Lyngdorf Audio) is and always has been owned by Peter Lyngdorf, the owner of Lyngdorf Family Holding ApS which is the parent company of NewAni A/S, AudioNord International A/S, DALI A/S, SL Audio A/S, Benelux, and Hi-Fi Klubben A/S. Lyngdorf is not owned by Steinway (AKA Steinway & Sons), it now is a part of Steinway Lyngdorf (AKA SL Audio A/S).
2) The Audio Precision AUX-0025, which is a low-pass pre-analyzer filter specifically designed to reduce the out-of-band energy in the output signals of switch-mode amplifiers, should have been used with the Audio Precision audio analyzer instead of the S-AES17, which is a pre-analyzer filter used when measuring DAC outputs (the TDAI-3400 does not have a DAC output.) Therefore your measurements are faulty.

Founder/Admin

2) The Audio Precision AUX-0025, which is a low-pass pre-analyzer filter specifically designed to reduce the out-of-band energy in the output signals of switch-mode amplifiers, should have been used with the Audio Precision audio analyzer instead of the S-AES17, which is a pre-analyzer filter used when measuring DAC outputs (the TDAI-3400 does not have a DAC output.) Therefore your measurements are faulty.

That aside, I used the Audio Precision AUX-0040 for filtering, not AES-17 analog filter you are assuming. I referenced AES-17 with respect to band limiting, not the actual device used.

I prefer AUX-0040 with its flat 40 kHz response in the age of high-resolution audio, as opposed to AUX-0025 which is for 20 kHz bandwidth. AES spec allows either to be used as long as the bandwidth is specified.

Member

Yes, but that is an auxiliary output. It really is meant for driving analogue subwoofers, and nothing else.
A TDAI's analogue line output is generated by the DAC portion of a cheapish multi-channel codec, a chip whose
main reason for being in there is that it performs the microphone interfacing for RoomPerfect.

The core of the TDAI design is in its digital-only signal path that eschews a traditional DAC. Instead it
takes a digital input signal, resamples it to 96kHz, converts to a pulse-width stream which directly
drives the power transistors. The DS modulator creates a mountain of ultrasonic noise, as they all do,
and this starts right above 20kHz. Which is why you need a 20kHz filter for traditional distortion testing to
be meaningful.

Volume control is performed by controlling the output stage's supply voltage. At least, this is the case for
volume settings of 0dB down to -24dB. Below -24dB traditional digital attenuation is used.

For the aux analogue output digital attenuation is used for the entire range. Obviously.

Another important aspect is that the output stage is a bridge with a unipolar supply. Both speaker terminals
have thus a common-mode DC potential. What of course matters is their differential mode signal, which is what
the speaker sees and which does not contain any DC. I hope you measured differentially, and not relative to ground.
But I have a feeling you did not do this, which may explain a thing or two.

Founder/Admin

Yes, but that is an auxiliary output. It really is meant for driving analogue subwoofers, and nothing else.
A TDAI's analogue line output is generated by the DAC portion of a cheapish multi-channel codec, a chip whose
main reason for being in there is that it performs the microphone interfacing for RoomPerfect.

I see your point. But I see no mention of that anywhere in the documentation or marketing material for the product. What you saying is that if I want to use external amplification for more power, I should not. This should be clear in the documentation. Seeing how the amplifier is the much weaker link than the DAC, that would be a bad thing in global scheme of things.

Also, what on earth is a cheap DAC doing in a $6,500 product? We have $99 DACs that run circles around it.

Founder/Admin

The core of the TDAI design is in its digital-only signal path that eschews a traditional DAC. Instead it
takes a digital input signal, resamples it to 96kHz, converts to a pulse-width stream which directly
drives the power transistors. The DS modulator creates a mountain of ultrasonic noise, as they all do,
and this starts right above 20kHz. Which is why you need a 20kHz filter for traditional distortion testing to
be meaningful.

That maybe made sense 20 years ago. Today, people have high-resolution content and they like to think what they get above 20 kHz is what is in the music, not a heap of ultrasonic noise. Here is the fact sheet from Lyngdorf on TDAI-3400:

Over USB it supports sampling rates up to 384 kHz. That would give us a bandwidth of 384/2 = 192 kHz. Yes, usually that is more limited in practice so let's round that down to 100 khz. You are telling me that I am not entitled to any of that between 20 kHz and 100 kHz?

The notion that I should put filters in measurements to produce conditions that do not match what users have is just wrong in my book. I am not here to bend to what the product limitations are. I have tested many other switching amplifiers without the condition you mention.

In this day and age, high-end products must be able to reproduce high-resolution content. There is no reason to make excuses for it because the designer chose an architecture that doesn't work right there.

Even if I were to do as you say, there better be documentation to this effect. It needs to say that this product produces tons of ultrasonic distortion above 20 kHz so it is not suitable for high-resolution audio and such. If we are going to hide this, then the consequences are that reviews like mine come out and people are shocked to read it for the first time. As it seems to have happened.

Beside the points I made in the last post, keep in mind that I do limit the bandwidth to 22 kHz in addition to external AES filter:

Look at the bottom right: bandwidth is "DC to 22.4 kHz." So I am already helping manufacturers there by filtering the output even though no customer does that.

Even with that additional filter, we are still killed with harmonics that rise to -80 dB so no way you can get a SINAD better than that. What are we doing creating such high harmonic distortion in a multi-thousand dollar amplifier?

Here is the Hypex NC400 with same power output:

Dominant distortion is 3rd harmonic at -112 dB. That is a 40 dB improvement over Lyngdorf!!!

There is a ton of marketing material dedicated to how great the amplification portion of TDAI-3400 is. In reality it is not even remotely competitive with other switching amplifier designs. They would have been much better if they used Hypex modules and relied on the rest of the features to sell the product.

You can't reinvent the wheel, create far worse performance and when that is shown in measurements, say that measurements need to be limited to hide them. There is no hiding here anyway, filter or not.

Founder/Admin

Another important aspect is that the output stage is a bridge with a unipolar supply. Both speaker terminals
have thus a common-mode DC potential. What of course matters is their differential mode signal, which is what
the speaker sees and which does not contain any DC. I hope you measured differentially, and not relative to ground.
But I have a feeling you did not do this, which may explain a thing or two.

You need not rely on your feelings. Instead you can either read the specs of my analyzer or just ask me. All speaker output measurements are done using the differential inputs on Audio Precision. Here is screen cap of the dashboard measurement for example:

Disappointing to see you put so little trust in my work, yet put all the wind you can behind manufacture.

You mean the tiny blurbs that that Paul's measurements have shrunk to these days?

Even that tiny bit matches my testing. To with, here is the second graph:

The black portion is THD+N for 1 kHz tone as power is increased. The one in blue is for 20 kHz. Notice the massive increase in THD+N for 20 kHz. Even its best case scenario at around -16 dB has SINAD of 42 dB!

I should have remembered to run jitter test as Paul did:

That is 2.1 nanoseconds of jitter which is pretty high. Typical jitter data needs to be less than 250 nanoseconds to preserve 16 bit data at 20 kHz. This is an order magnitude higher than it should be.

Overall, I see nothing positive in the measurement section to counter what I have measured.

I don't know how the sound quality rating is arrived at but it is at 84%:

Member

That aside, I used the Audio Precision AUX-0040 for filtering, not AES-17 analog filter you are assuming. I referenced AES-17 with respect to band limiting, not the actual device used.

I prefer AUX-0040 with its flat 40 kHz response in the age of high-resolution audio, as opposed to AUX-0025 which is for 20 kHz bandwidth. AES spec allows either to be used as long as the bandwidth is specified.

I didn't see a digital output listed on the website (I now see that they only list the inputs), so I downloaded the Owner's Manual and found the digital output -- thanks.

You didn't mention the AUX-0040 filter but you did mention the AES-17 filter in your review posting, so I assumed you didn't use a switching mode filter. And when you said, "Audio Precision software decided to just show a DC measurement in the scope graph and would refuse to give me a reliable power measurement. I was going crazy until I realized there was fair bit of DC leakage out of the unit. So I told the AP to use AC measurement and that all of a sudden cured the problem..." it did appear that you didn't understand that this amp drives both speakers in bridge mode (I've been told that Kirchner ATB equipment is better at measuring the Lyngdorf amp than Audio Precision.) And of all of the reviews I've read about the Toccata/TI based amps, this was the first bad review. Perhaps you could provide more information in your narrative so as not to leave gaps for fools to fall in.

No, I'm not affiliated with any of Peter Lyngdorf's companies -- I was just a customer. I do have a friend who has done work on the Millennium amp, a friend who was a TacT Audio dealer, another friend who is a Lyngdorf dealer, and I have exchanged some personal messages with Peter (he wanted me to have the first pair of TacT Audio W410 corner-woofers). I have 5 TacT Audio S2150 digital amps, have had the RCS 2.0, RCS 2.2X, and currently have the TCS mkIII processor, and have the MH1, C1, and W410 speakers. Peter was the founder and co-owner of TacT Audio along with Radomir "Boz" Bozovic; when they split up, Boz took TacT Audio and the room correction algorithm he had developed, while Peter started Lyngdorf Audio and took the speakers he had provided, and they both shared the digital amps that were developed by Toccata, which Peter had funded and TI had bought. So it's more like Peter is affiliated with my money than I am with him.

As you were not familiar with Peter's audio empire, you may like to know that in addition to the companies he owns, he also is a co-owner of Purifi ApS along with Bruno Putzeys and Lars Risbo.

I don't write books or lengthy paid reviews. My reviews are brief and follow similar measurements and techniques across same class of products. So regular readers can follow what is being done. I realize you are new so not as familiar with them. The answer to that would be to ask clarifying questions, and not assuming I don't know what a switching amplifier is and how to measure it.

I own a TCS MK ii. It started to have problems after being upgraded for $5,000 to Mark ii. This was on top of original $10,000 purchase price (total $15,000). I downloaded new firmware from Tact website which bricked the unit. Contacted Boz and he told me to get lost because the unit was discontinued and I had no business upgrading its firmware.